Metal powder feed mechanism



April 1951 J. A. HARRINGTON METAL POWDER FEED MECHANISM e Sheets-Sheet 1 Filed Sept. 19, 1946 T M m M 5W Juhin A-Harrzz'z AIWig 1951 J. A. HARRINGTON 2,550,653

METAL POWDER FEED MECHANISM Filed Sept. 19, 1946 6 Sheets-Sheet 2 5 Jim A Harz"zz2gimz April 24, 195 J. A. HARRINGTON METAL POWDER FEED MECHANISM 6 Sheets-Sheet Filed Sept. 19, 1946 UN mmmuwm NZMM OP wuZC. 34 .54 75:35 .WP mmmuum .rzomu OP wmsmmwmm E632 maw VN mmmuum PZQNE OP 35043 mm mmmoum mmPZmU m9 OP Z33u WQ m@ J QM April 24, 195 J. A. HARRINGTON METAL POWDER FEED MECHANISM Filed Sept. 19, 1946 6 Sheets-Sheet 4 mm ww .m mm, mm w. W x A AI 0 Q) Q EM Fm //#W n w 1 ERM /4,

April 1951 J. A. HARRLNGTON' 2,550,653

METAL POWDER FEED MECHANISM Filed Sept. 19, 1946 e Sheets-Sheet 5' l I l h H. J "In Ilium HIMI will! l-mlh 3M JmnAHarrzngzm .3 1; 'g

Patented Apr. 24, 1951 UNITED STATES PATENT" OFFICE METAL POWDER FEED MECHANISM John Harrington, Minneapolis,-Minn. (Application September 19, 1946, se'ral No. 97,936

4 Claims. (01. 7s- -.5) j

This invention relates to the art of cold pressing metal powders to. form pellets commonly known as compacts," and has particular reference to mechanism for feeding or charging such metal powders into the die cavities of powder metal presses.

In the past considerable difficulty was experienced in charging the die cavities of metal powder presses due chiefly to the poor flow characteristics of the powder being used and the consequent difliculties entailed in assuring complete filling of the die cavities to uniform densities. In many instances, forexample, when using tungsten carbide powders whose flow characteristics are extremely poor, it has been necessary to fill the die cavities of metal powder presses by hand to insure against the presence of void spaces in the cavities at the time of the pressing operation.

Needless to say, such hand charging wastes considerable time and efiort and renders the pressing operation quite costly.

Other types of powders used in cold pressing oxidize extremely rapidly and it is almost impossible to fill die cavities with these rapidly oxidizing powders without oxidation to a degree destroying some of the bonding features of the powder which are vital to the cold pressing operation.

With these objections to past practices in mind, it is an object of the present invention to provide feed mechanism by which the charging of die cavities of metalpowder presses is greatly facil itated and complete filling of the cavities to uniform densities assured. I V s It is another obiect of this invention to provide feed mechanism for charging metal powder into the die cavities of metal powder presses in a much more rapid and uniform manner than heretofore and which is capable of efficiently handling powders having extremely poor flow characteristics.

Still another object'of this invention "resides in the provision of mechanism for automatically re-' charging the die cavities of metal powder presses after each pressing operation.

A further objectof this invention is to provide feed mechanism for charging the'die cavities of metal powder presses which is of unitary design so'as to enable the mechanism to be readily at-' tached to and used with any conventional metal powder press.

A still further object of this invention resides in the provision of feed mechanism for charging the die cavities of metal powder presses which will prevent oxidation of metal powders which tend to oxidize extremely rapidly so as to preserve the bonding features of the powder so vital to the cold pressing operation.

Another object of this invention resides in the provision of novel feed mechanism by which metal powder is injected into the die cavities of metalpowder presses under gas pressure to more positively control the transfer of powder from a source to the die cavities.

A still further object ofthis invention resides in the provision of feed mechanism by which metal powder is charged into the die cavity of a metal powder press wherein a nozzle-like feed head 'reciprocable over the die cavity toward and from an operative position above the cavity is employed for the purpose of injecting the metal powder in' the cavity.'

Another object of this invention resides in the provision of feed mechanism for automatically recharging the die cavities of metal powder presses after each pressing operation in. which waste of powder during the charging operation is practically eliminated.

With the above and other objects in view which will appear as the description proceeds, this invention resides in the novel construction, combination and arrangements of parts substan tially as hereinafter described, and more particu-'- larly defined by the appended claims, it being understood that such changes in the precise embodiment of the hereindisclosed invention may be made as come within the scope of the claims;

The accompanying drawings illustrate one complete example of the physical embodiment of the invention constructed in accordance with the best mod so far devised for the practical application of the principles thereof, andin'which:

Figure 1 is a siddeleva'tiona'l view of the feed mechanism ofthis invention showing the manner of its attachment to a" metal powder press only a portion of which is indicated; Y

Figure 2 is a plan view of the mechanism shown in Figure 1;

Figure 3 is an end view of the feed mechanism shown in Figure 1 looking toward the press upon which the feed mechanism ismounted;

Figure 4 is an enlarged plan view of the feed head assembly (shown in Figure 2) with parts thereof broken away to show the interior con struction of the head;

Figure 5 is'a bottom view of the feed head as sembly shown in Figure 4 illustrating the underside thereof;

Figure 6 is an enlarged longitudinal sectional view. through the feed headassembly takenalong I the plane of the line 6-6 of Figure 2 and showing the head in charging position over the die cavity of a metal powder press;

Figure 6a is an enlarged and fragmentary cross sectional view of the front portion of the feed head;

Figure '7 is a view taken on the plane of the line 1-1 of Figure 6 defined by the joint between the feedhead per se and the flange coupling attached thereto and looking toward the feed head;

Figure 8 is a view taken on the plane 88 of Figure 6 defined by said joint between the feed head per se and the flange coupling looking toward the latter; and h V Figure 9 is a combined electrical and hydraulic control diagram by which the feed-mechanism automatically governed to effect recharging of a die cavity after each pressing operation.

Referring now more particularly to the .accoi'n panying drawings in which like numerals indicate like parts throughout the-several views, the nu--- m'era-l H1 generally designates the feed mechanism of this invention. The feed mechanis-m 10 may 'be attached to the bolster plate H, with which metal powder presses are provided,- along-- side the die block l2 which is mounted on the top face of the bolster plate. The die block may contain a plurality of die cavities in its top surface, but only one such cavity [-3 has been illustrated.

In the type of metal powder press hereinillustrated, a hydraulic compressor cylinder !4 is 10-- cated above the die block and has a plunger l5 .augnmg with and fitting the die cavity. The plunger I5 is adapted to be forced down into the cavity when the same is filled with metal powder to" compact the powder between it and the plunger 16 of a hydraulic ejector cylinder I! mounted be- Heath the die cavity.

Inasmuch as the press forms no specific part of the present invention, only those parts thereof necessary to an understanding of the invention have been indicated in Figures l and 6 and in the combined electrical and hydraulic control diagram of Figure 9.

The particular manner of mounting the feed mechanism on the press is clearly shown in Figures l, 2 and 3 where it will be noted that the imit comprises a supporting plate 20 secured by means of screws 2i to the side of the bolster plate H.- The plate 20 isprovided withvertical flanges 22 at opposite sides thereof between which the legs 2'3 of a supporting bracket 24 are re-' ceived.-

The outside edges of the legs 23 taper inwardly reaiwardly' of the mounting plate '20 and are spaced 3; distance from the flanges 22 of the mounting plate such as to enable gibs 25 to be inserted between the legs and the flanges. These gibs have inclined surfaces overlapping the incli-fied surfaces or the legs 23 so that upon secure ment of the gibs to the mounting plate 2|] as by means of screws 26 a vertical slideway' is provided for the legs of the bracket 24 by which the bracket is held in any desired position of vertical adjustment upon the mounting plate 20.

As will be" apparent, it is necessary to loosen only one of the gibs 25'for the purpose of freemg the bracket 24' for vertical adjustment of the feed mechanism, and such adjustment is facilitated by turning one of a pair of nuts 21' threaded on a: stud 2'8 anchored in the bracket 24. The nuts 21 are disposed at opposite'sides of a.- lug 28 having an oversized aperture through which the stud passes.

The mechanism it includes a feed head: a

" thereon by bein confined between opposite gibs 35 secured onto the top surface 33 of the bracket as by means of screws 36. It is to be noted that theinner sides of the gibs have inclined surfaces substantially overlapping similarly inclined surfaces along the side edges of the slide so as to preclude all motion of the slide relative to its supporting bracket except horizontal reciprocatory motion of the slide. Longitudinal side rails 31 on. the supporting bracket projecting up fromthe top surface thereof provide backing for the outer sides of the gibs 35.

The feed head assembly is connected with the slide 3| to reciprocate therewith by means of a yoke 38. The forked extremity of the yoke embraces the feed head and is pivotally connected to opposite sides thereof as at 39 so as to enable a limited degree of pivotal 0r rocking motion of the feed head assembly on a horizontal axis transverse to the direction of feed head motion.

The endof the yoke opposite its forked extremity flatwise abuts the adjacent end of the slide 3| and has a single stud 40 projectin centrally rearwardly therefrom toward the slide 31 and received in a hole 4| in the end of the slide. The hole 41 for the stud 40 leads from the outer end of the slide adjacent to the feed head assembly rearwardly to an opening 42 through the slide which is provided to enable a pair of nuts 43 to be threaded onto the outer end of the stud and hold the yoke and. feed head assembly driving-lyconnected with the slide.

The rear of the slide opposite the feed head mechanism extends outwardly beyondthe supporting bracket 24 and has a depending connector bracket 43 fixed to its underside by which the slide is connected to the plunger 44 of a hydraulic feed cylinder 45. The cylinder 45' is fixedly supported in any suitable manner from the bracket '24- beneath the top thereof and is connectible with a source of fluid under pressure to effect extension and retraction of it plunger 44 and to thereby cause reciprocation of the feed head assembly toward and from its operative position over the die cavity I3 of the press.

Electric and hydraulic mechanism to be later described is employed to automatically control advancing and retracting motion of the feed head assembly by means of the hydraulic feed cylinder 45 in synchronization with the operation or work cycle-of the press.

The feed head assembly as best illustrated in Figures 4, 5, 6, 7 and 8 comprises a nozzle-like head 50, and a flange coupling 5i attached to the rear of the head 53 as by means of screws 5|.

The nozzle-like feed head- 58 is comprised of two main castings Hand 53 secured together fiatwise in superimposed relationship with respect to one another. The lower casting 53 has a substantially large central port or hole 54 therein leading from the bottom of the head to the underside of the castin 52 forming the top of the feed head, and the upper casting 5.2 hasa shallow upper portion of the hole 54 adjacentthereto by 'a screen 56 which has a mesh fine enough to preelude the passage of metal powder therethrough.

A circular distributing plate 51 is secured by suitable screws to the bottom of the head casting 53 to extend across the mouth of the hole 54 therein, a'ndhas a multiplicity of holes 53 therein located along. circumferential but radially spaced centerlines. I

- In addition, the lower face of the distributing "plate 51 has a series of annular deflector ribs 59 on its underside located between the adjacent circumferential rows of holes and all of the ribs are inclined downwardly and inwardly toward the center of the plate so that metal powderintroduced into the central chamber in the lower casting of the feed head is directed downwardly through the holes 53 and then inwardly by the ribs toward the central axis of the distributing plate and into a die cavity'over which the head maybe centered.

The hole 54 provides a central feed chamber inside the head beneath the screen 56 into which metal powder is adapted to be introduced and blown from the head through the mouth of the hole 54 and the distributing plate extending thereacross into the die cavity. The concept of blowing metal powders into the die cavities of metal powder presses is one of the main features of this invention for it enables charging of the die cavities with powder without formation of voids and results in filling of the cavities to a uniformity of density heretofore impossible.

-.Powder metal is conducted to the chamber provided by the hole 54in the feed head through a passage't'i l" in the lower head casting 53 exteridingrearwardly from the upperportion of the hole 541:0 the front of the flange coupling 5i where it connects with a powder supply passage 55 leading rearwardly through the entire flange coupling.

It is to be understood that the head and coupling are joined together in airtight fashion so as to preclude leakage at the joint therebetween.

'A hose 6| attached to the rear of the coupling in communication with the supply passage is provided to supply the nozzle-like feed head with metal powder from a source thereof such as the powder hopper 62, illustrated diagrammatically in Figure 9.

In accordance with the present invention'the hose line 6! is adapted to be connected with a suitable source of gas or air under pressure through an electromagnetic valve VI, and the feed hopper 52 has a restricted bottom discharge tube 53 opening into the hose line B! substantially at the constriction of a venturi 55 therein located between the valve and the feed head assembly.

When the valve V! is energized to open the same, air or gas under pressure flows through the line 6] and has its velocity increased a substantial amount upon entering the venturi to effect a corresponding reduction in pressure by which powder metal is drawn from the hopper and entrainedin the air or gas stream to be carried thereby into the feed head 56 for discharge through the distributing plate and injection under pressure into the die cavity l3.

Powder metal issuing from the apertures of the distributing plate 5! at the mouth of the hole 54 in the feed head is prevented from escaping from the underside of the head by an annular elastic sealing and wiping gasket 68 secured to 6 the underside of the head and surroundingthe distributing plate 57 in radially spaced relation thereto. The weight of the feed head is suflicient to hold the elastic sealing and wiping gasket under compression between the top face of the die block and the underside of the head to establish 5 an air tight joint therebetween.

The recess 55 in the head above the screen 56 communicates through a passage 55" leading rearwardly therefrom with a passage 12 extending endwise through the flange coupling 5|. A hose line 13 connects with the flange coupling 5| in communication withthe passage 72 thereof and has one branch 13 thereof connected with a source of air or gas under pressure (not shown) through an electromagnetic valve V2 adapted to be energized and opened at the time metal powder is being conducted to the head and injected into the die cavity l3.

After filling of the die cavity, the valve V2 in the hose line 13 is adapted to be closed to disconnect the recess '55 from said source of pressure and an electromagnetic valve V3 located in a second branch 13 of the hose l3 opened to cause the recess 55 to be subjected to vacuum from a source thereof (not shown) to which the branch line 13" leads. This vacuum effects the extraction of as much'air or gasas possible from the die cavity and the space beneath the feed head.

During the application of suction to the recess 55 in the head, it is the purpose of the screen 56 to block passage of metal powder upwardly and out of the head through the flange coupling passage T2.

The upper head casting 52 is provided with inner and outer arcuate recesses 14 and 15 opening to its underside adjacent to the lower casting 53 and which extend about the front rim of the upper casting to have their opposite ends termi nate just ahead of the fork connection to the feed head. The recesses M and 15 are concentric to the axis of the hole 54 which provides the feed chamber and discharge port for the feed head, and are separated from one another by a relatively thin arcuate web 76.

The inner recess 14 has greater Width than the outer recess i5 and is adapted to constitute a vacuum manifold while the relatively narrow recess 15 is adapted to constitute a pressure manifold for a purpose to be shortly described.

The lower head casting 53 has similar recesses 18 and 19 opening to the bottom thereof and extending arcuately about the rear of the feed head-with their opposite ends terminating just to the'rear of the fork connection to the feed head as indicated in Figure 4. The recesse 18 and (9 are likewise concentric to the discharge port 54 of the head and their radial distances from the center of the port 54 are the same as for the front recesses 14 and 15 respectively. The inner recess i8 has greater width than the outer recess 19, and these rear recesses likewise constitute vacuum and pressure manifolds respectively. a

It is to be noted that the arcuate recesses I and 79 in the rear of the lower head casting-53 open directly to the bottom thereof while the arcuate recesses 54 and 15 in the front of the upper head casting open to the top face of the lower head casting. I

In order that the recesses 14 and 15 may be communicated with the space. beneath the feed head afforded by the sealing gasket 68, the front" portion of the lower head casting 53 is provided with two sets of apertures 8! and 82 closely spaced along concentric center lines directly beneathithe' 7. recesses. lo and '15, with. the apertures leadin around the entire front portion of. the lower easting to the. opposite ends of the recesses 14 and T thereabove.

The feed head 50 is also provided with a bottom ring, 85 secured to the underside of the lower head casting 53 in a position surrounding the distributing plate 51 and directly beneath the recesses 18 and T9 at the rear of the lower head casting and beneath the arcuate rows of apertures 8i and 82 in the front portion of the lower head casting.

The sealing. gasket 68 which has been previously described may be conveniently secured to the underside of the bottom ring as shown in Figure 6.

The bottom ring 85 has a multiplicity of nozzlelilre apertures 55 drilled therethrough at a downward and inward inclination and located along a circumferential center line just inside "the sealing gasket 68 and in line with apertures 82 and the outermost recess iii of the lower head casting, by which gas or air maintained under pressure in the outer recesses T5 and I9 discharges to the space beneath the head inside the confines of the gasket.

The inner peripheral portion 87 of the bottom ring 85 is directed inwardly and slightl downwardly so that it forms a conical surface extending completely around the rin lying beneath the innermost recess '53 in the rear portion of the lower casting 53 and to lie beneath the innermost set of aperture 8! in the front portion of the lower head casting.

The inner periphery 8? of the ring terminates adjacent but in spaced relation to a cylindrical flange 83 projecting from the lower face of the bottom Casting 53 and together with the flange defines anannular orifice 89 through which the space beneath the feed head may be subjected to vacuum when the innermost recesses Hi and 78 of the two head castings are connected with a source of suction.

During the charging operation when the feed head assembly is centered over the die cavity [3, air or gas under a light pressure issues from the multiplicity of apertures 86 to agitate or stir up the metal powder collecting on the face of the die block so that such powder may be picked up and exhausted through the annular orifice 89' located radially inwardly from the pressure nozzles 86.

The arcuate recess 75 at the front of the head is supplied with air or gas under pressure through a passage 15 (see Figures i and 7) extending rearwardly therefrom through the upper casting 52 at one side of the casting to align and (3-0111- municate with a passage 9| running rearwardly through the coupling 5!. A hose 92 connects the coupling passage 9| with a suitable source of air or inert gas under pressure through an electromagnetic valve V4.

' Vacuum is applied to the arcuate recess 14 inthe front of the head through a passage 14' thereof (see Figures 4 and 7) extending rearwardlythrough the upper head casting at the side thereof opposite the passage 15, to align and communicate with a passage 93 running rearwardly through the coupling 5i. A hose 94 connects the coupling passage 93' with a vacuum pump, not shown, through an electromagnetic valve V5.

The arcuate rear recess 19 in the lower head casting 53 communicates through a passage 19 leading rearwardly therefrom with a passage 98 running rearwardly through the coupling 5| beneath the passage -93 therein. A hose. 91 cons. nects the passage -96 with the source of air 0.1 as under pressure and supplies the rear pressure chamber 19- with such air or gas.

The arcuate vacuum recess 18 in the rear of the lower head casting 53 is communicated through a passage 18' leading rearwardly therefrom with a passage 98 leading endwise through the flange coupling 5| beneath the passage 9| therein, and a hose Hill is provided to connect the passage 98 with a suitable vacuum pump, not shown.

As will be later described, the vacuum and pressure in the arcuate front recesses T4 and 15, respectively, is maintained only for the period of time in which the feed head is substantially centered over the die cavity to charge the same, and is adapted to be automatically shut off by the electromagnetic valves V5 and V4 in the hose lines 9 2- and 92, respectively, whenever the feed head is in its retracted position or is traveling to or from its operative charging position; and vacuum and pressure in the arcuate rear recesses 15 and 19, respectively, is adapted to be maintained all the time inasmuch as such pressure and vacuum applied to the face of the die block at the rear of the feed head is incapable of interfering with proper charging or wiping of the die block.

Suitable control means diagrammatically illus-- trated in Figure 9 is employed to automatically determine when-the arcuate recesses in the feed head are to be subjected to pressure and vacuum during operation of the feed head, and in addition controls the charging of metal powder into the die cavity by the head and automatically governs reciprocation of the feed head mechanism between its operative charging and inoperative retracted positions.

As herein shown the hydraulic feed cylinder 45 for'the feed slide 31 has its opposite ends selectivel connectible with a source of hydraulic fluid under pressure through a four way hydraulic valve unit llilby means of fluid ducts ill and H2. Fluid under pressure enteringthe cylinder through the duct H2 efiects ad- Vance of the feed head, while fluid entering the cylinder through the duct Ill effects retraction of the feed head.

The hydraulic valve unit I ll] is of the electro magnetic type and has a pair of solenoids H3 and lid for shifting the spool-like piston H5 of the valve in opposite directions from its neutral position shown at which it closes oiT the ducts ill and H2 of the cylinder 45 to preclude the flow of fluid under pressure to the drive cylinder.

Energization of the solenoid H4 pushes the piston H5 of the valve to the right-in the valve casing from its neutral position shown to connect the duct ill of the cylinder 45 with .a duct H5 leading from the outlet of a hydraulic pump. ill through the valve H0; while energization of the solenoid H3 pushes the piston H5 of the valve unit to the left from its neutral position -to conect the duct H2 with the pressure duct H6 through the valve.

It is to be understood that the pump ii! is driven by a suitable electric motor H8 and that the inlet of the pump is communicated through a duct H9 with a fluid reservoir lZll to supply liquid to the pump.

When the hydraulic drive cylinder is connected with the source of fluid pressure by ener-. gization of the solenoid lid as described, the plunger 44 of. the cylinder is caused to travel to :9 the left as seen in the diagram andthrough its connection with the feed slide 3| effects retraction of the feed head assmblyte from over the die cavity to an inoperative position disposed over the apron32 (as shown in Figure 9).

Upon de-energization of the solenoid H4 and energization of the other solenoid M3 the spool like iston of the valve, IIO is shifted to, the left from its neutral position indicated to disconnect the right hand end of the hydraulic cylinder 45 from the pressure outlet or" the pump I I6 and to connect the opposite or left handend of the cylinder with the pressure outlet of the pump through the valve andthe pressure duct II2 to produce the advancing stroke'of thefeed head.

In the present case energization and de-energization of the solenoids; I I3 and I I4 is effected at the dictation. of relays I2I and I22, respectively, for the solenoids.

Fluid return ducts I323 leading from the opposite ends of the four way valve unit Hi] to the reservoir I26 enable the fluid exhausted from the hydraulic feed cylinder 45 by motion of its plunger to be conducted through one or the other of the ducts III or IIZ to the reservoir through the valve unit III} in an obvious manner.

One of the main features of the control system of this invention resides in the fact that it is adapted for automatic operation after each work cycle of the metal powder press to which the feed mechanism is attached.

Since the compressor and ejector cylinders I4 and ll ,of the press are operated sequentially and the work cycle of the press customarily carried through automatically, the ejection of the compact after each pressing operation by the plunger of the ejector cylinder occurs substantially at the end of the work cycle of the press and the retraction of the plunger II; of the ejector cylinder may be considered the final motion of the press to terminate the work cycle.

In the present case it is the final motion of the press as understood to be the retraction of the ejector plunger IE to itsposition defining the bottom of the die cavity seen in the diagram which initiates the feed stroke and consequently the start of the cycle of operation of the feed head mechanism. r

As seen in the diagram, the plunger I6 of the ejector cylinder carries an arm I25 medially pivoted from the plunger, asat I25 to swing on a horizontal axis. The arm has its inner end adjacent to the plunger I6 weighted .to normally rest against a collar I21 on the plunger and thereby hold the outer end of the arm in an extended substantially'horizontal position in which it engages the actuator of an automatic start switch I23 and .closes the switchon the down stroke of the ejector cylinder.

. Engagement of'the projecting end of the arm with the actuator of the automatic start switch I28 on the upward ejectorstroke of the plunger I5 merely produces pivotal motion of the arm in a counterclockwise direction to cause it to ride over the switch actuator without closing the switch. 7 V

The contacts of the automatic start switch I28 when momentarily. bridged in this manner establish an energizing circuit through the coil I30 of the relay I2! whichuponclosure effects energization of the feed solenoid .;I I3 of the electromagnetic valve unit IIll. This energizing circuit for the coil I36 leads from-lineLI through a conductor I32 to one side of the: switch I28 and through. a conductor I33 leading from the other 10 side of the switch connects with one' endiof the coil I30 of the relay I2I. A conductor I34 connects theother end of .the coil I30 with the line L2 to complete the energizingcircuit for the coil I38 thereby causing the relay I2I to close.

The relay I2I has two. setsof stationary con-1 tacts' I35 and I38 which are bridged upon energization of the coil I30 in the manner described. Bridging of the relay contacts I36 establishes a holding circuit for the relay I2 I, while bridging of the relay contacts I35 effects completion of an energizing circuit-for the feed solenoid I I3 of the electromagnetic valve unit III) tomove the spoollike plunger I I5 of the unit to the left and thereby initiate the feed stroke of the feed head.

'lhe, energizingycircuitsfor both of the, valve solenoids H3 and H4, however, depend upon the positionsof a pair of double-throw limit switches I39 and I40 mounted on the supporting bracket 24. near the rear thereof but at opposite sides of the bracket.

Each of, theselimit switches has a depressible plunger-like button I4I extending vertically upwardlytherefrom so as to lie in the path of cams I43 and I44 adjustably carried by the feedhead slide 3I, and to be depressed by,the cams in the operative charging and inoperative retracted positions of the-feed head. I I

In order to provide for their adjustment, the cams I43 and I44 ar mounted on blocks I45 slidably disposed in adjacent track-like grooves I46 in the top surface of the feed slide running longitudinally thereof, A clamping strip J41 screwed onto the feed slide and common to both grooves overhangs the grooves to exert clamping pressure on the inner portions of the blocks I45, while separate strips I48 screwed onto theslide 3I at opposite sides of thestrip I41 engage and exert clamping pressureionthe outer portions of theblocksl45. I I I In this manner, the blocks with cams attached can be individually adjusted to any desired position longitudinally of the feed slide merely by loosening the screws for the clamping strips and held insuch position by the clamping strips I41 and I48 when the same are tightened down against the blocks. I r

For convenience, the limit switches havebeen shown upsidedownin the diagram with their contactors biased downwardlyto remain insuch positions unlessactuated by the cams I43and' I44. It will be apparent, therefore, that the limit switches I39 and I40 may be employed to determine the magnitude of feed head mechanism... v a

The cam I43 is so disposed longitudinally-of the feed slide, 3| that it engagesand depresses the button of the'switoh I39 .tomove the con-' tactor I5I of the switch out of its normal position against biasing .force thereon tending to hold the sameengaged with one set of stationary contacts I49 of the switch to an actuated position bridging the second set. I50 of stationary contacts at the time the feed head reaches its desired charging position shown in Figures 1 and 2. I

The cam I44 is so located on the feed slide that it engages and depresses the button of the switch I40 to move the contactor'. I54 of this switch out of its normal position against a' biasing force thereon tending to hold the same engaged with one set of stationary. contacts I52 of the switch to an actuated. position .bridging. the second set I53 of stationary contacts of the switch at the time the feed head reachesuits retracted position.

Withzthe feed slide-3I in its inoperativerereciprocation of the V i 'i tracted position "shown in the diagram, the cam M3 is spaced from its limit switch I39 and consequently the contacts I49 or the switch are bridged by the contactor I5I-, while the contacts I50 are open. In the retracted position of the feed slide, however, the cam I44 is in engagement with the button of the limit switch I40 to hold its contactor I54 off the normally bridged contacts I52 and in bridging relationship with the nor many open stationary contacts I53 of the switch.

It will be readilyseen therefore, that the holding circuit for the coil I30 of relay I2I and the energizing circuit for the feed solenoid 3 of the valve IIO can be completed only in the retracted position of the feed slide at which time the stationary contacts I49 of the limit switch 139 are bridged.

As will appear later-,- energizatien or the re tracting solenoid I14 of the valve I I by its rela 12 2 likewise depends stingin of the normally closed stationary contacts I52 of the li n'l'its witch I40, which condition obtains in all but the retracted position of the feed-slide. I

In the retracted position of the reed head shown in the diagrar n thereto-re; the holding circuitror the coil of relay I2I leads through a con--- ductor I56 connected with line LI, onto a conductor I51 joining one of the stationary contacts 4 53 with one of the stationary contacts I50 of the limit switches I40 and I39, respectively, and through a jumper I53 connecting the conductor I51 with the now bridged stationary contacts I49 of the switch I39, across the contactor I5I of the switch onto a conductor I 59 connecting with one of each set contacts I35 and I36 of relay I2-I, across the now bridged contacts I36 of the relay and onto theconductor L3 leading to one end or the coil I30, With the circuit through the coil completed by the conductor I34 joining the other end of the coil with the line L2.

. Bridging or the stationary contacts 135 or the relay I21 effects energization of the reed olenoid II? of the valve unit 1-10 by a circuit leading. from line LI and including the conductors I 59, I51, I53, the bridged contacts I49 of the limit switch "I39; conductor I59; the now bridged contacts I35 of relay I2I, a conductor I60 leading tonne end or the solenoid I13, and a conductor 'I't l leading from the apposite end of solenoid M3 to line L2. 5

- Tlic plunger :5 of the valve II 0 is thus caused to be inove'd to the left :from :its neutral iposi tioh indicated to connect the hydraulic .Lf'eed cylinder '45 with the outlet 'of the pump H 6 through the duct II2 producing the advancing stroke "of the feed head.

The feed head is advanced by the cylinder 45 until the head is brought to its operative charg ing'position centered over the die-cavity, at which time the cam its on the feed slide depresses the button of the limit switch I39 to open the stat tionary 'contacts I49 thereof and eifect bridging-of the stationary contacts I50 of the switch.

Since the stationary contacts I49 of the limit switch I39 are connected in the holding circuit for the relay I2I as well as the energizing circhit for the solenoid N3 of the electromagnetic valvev unit I10, actuation of the limit switch by the cam I 43 in this manner immediately effects dc 'energization of the coil I30 causing the relay III to open and also effecting de-energization of the solenoid II9 for the -'electromagnetic valve unit I I0.

Upon de=energization of the solenoid 1 I3, the spool like wpiston N5 of "the valve returns to its 12 neutral position to which it is biased closing the valve ports leading-ito the ducts iI I I and .I I2 thereby shutting on the hydraulic cylinder 45 from the source of pressure and causing the feed head to remain in its operative position centered over the die cavity I 3.

The feed head remains in this position while the die cavity is charged with metal powder during which time the various passages and chambers in the head are subjected to air or gas pressure or vacuum for the control of the charging operation.

Powder metal is delivered to the interior of the feed head for injection into the die cavity upon bridging of the normally opened contacts I50 of the limit switch I39 at the time the feed head reaches its operative position centered over the die cavity. When the contacts I50 are thus bridged, an energizing circuit is completed for the electromagnetic valve VI located in the hose line 6| between the source of air or gas under pressure and the metal powder hopper 62 so as to cause the valve to open. Air or gas flowing through the hose 6| toward the feed head draws metal powder from the hopper and such powder becomes entrained in the air or gas streamuto be delivered to the feed head thereby.

The energizing circuit for the solenoid of the valve VI leads through the now closed contacts I50 of the limit switch (I39 from the conductors I51 and I56 joined to line LI, and includes a conductor I10 which joins with a conductor I1I connecting one end of the coils of a pair of time delay relays I12 and 113, continues through the contactor I14 of the relay I12 onto a conductor I15 which leads to one side of the solenoid for valve VI, and is completed .from the other side of said solenoid by a conductor I16 and a conductor I11 joined thereto and leading to line L2.

At the same time that bridging of the contacts I50 of the limit switch I39 eiiects delivery of metal powder entrained in air or gas under pressure to the interior of the feed head to be blown thereby into the die cavity, energizing circuits are established for the solenoids of electromagnetic valve's V4 and V5 in the hose lines 92 and 94, respectively, to cause said valves to open.

Opening of the valve V5 connects the vacuum recess 14 at the front of the head with the source of vacuum'throu'gh the hose line 94, while opening of the valve V4 connects the pressure recess 15 at the front of the head with the source of air or gas under pressure through the hose line 02. The solenoids of the valves V4 and V5 have one end thereof connected direct to line L2-, and are energized by bridging of the contacts I50 by means of conductors joined to the conductor I10 leading through the limit switch I39 to line LI.

The vacuum and pressure recesses 18 and 19,"

respectively, at the rearor the feed head remain connected with their sources of vacuum and air or gas under pressure, respectively, at all times during operation of the feed mechanism, and for this purpose manual valves IBTand I88 are placed in the hose lines I00 and 91, respectively; The valves I81 and I88 are adapted to be opened and left open whenever the feed head mechanism is placed in use.

As will be apparent from the diagram, bridging of the contacts I50 of the limit switch I39 at the time the feed head reaches its operative position also completes the energizing circuits to both time delay relays I12 and I13. As already stated, one end of the coil for each of these repowder.

lays is connected to conductor I19 leading to line of limitswitch I 39, therefore, starts the time delay periods for the two relays I12 and I13. It is to be understood that although the energizing circuits for relays I12 and I13 have been described as being completed at this time these relays have characteristics which prevent response of their contactors except after a suitable and adjustable time delay period.

As noted previously, the contactor I14 for the time delay relay I12 is connected to conductor HI, and in its normally open position engages a stationary contact I8I to which conductor I15 connects, as shown, to complete the energizing circuit for the solenoid 'of the valve VI concomitantly with bridging of the stationary contacts I59 of the limit switch I39. -The contactor' I14 of relay I12 remains in its normally open position maintaining the valve VI open to effect injection of metal powder into the die cavity until the expiration of the time delay period, which is set for a duration such as to insure complete filling of the die cavity with metal concomitantly with energization of the solenoid of the powder feed valve VI an energizing circuit is likewise established to the solenoid of the electromagnetic valve V2 in the branch 13' of hose line 13 leading to the recess 55 above the screen in the interior of the feed head to connect the recess with the source of air or gas under pressure.

The solenoid of the electromagnetic valve V2 is connected in parallel with the solenoid of the valve VI across the conductors I15 and I16 which lead to lines LI and L2, respectively, in h an obvious manner. Consequently, the recess 55 is subjected to pressure during the time metal powder is delivered to the feed head to facilitate injection of the powder into the die cavity.-

After a suitable period during which metal powder blows from the feed head into the die cavity and of sufficient duration to insurecomplete filling of the cavity, the delay period of relay I12 expires and its contactor I14 responds by swinging out of engagement with respect to contact WI and into engagement with a second stationary contact I92. Separation of contactor I14 from contact IBI effects de-energization and consequently closure ofthe metal powder feed valve VI and also closure of valve V2 to terminate the powder injection and shut off the pres sure to recess 55 in the head.

Since one end of the coil of valve V3 connected'direct to line L2 as indicated, engagement of the contactor I14 with the stationary contact I82 of the time delay relay I12 at the expiration of the time delay period then conthe completion of the powder injection period to.

effect extraction of any air or inert gas which 14 may have become trapped in the die cavity by the filling operation and to enable the metal powder in the cavity to settle to a uniform density desirable for the cold pressing operation.

The screen 56 separating the recess 55 from the remainder of the hollow interior of the feed head at this time precludes the passage of any metal powder upwardly into the recess 55.

After subjection of the interior of the feed head to vacuum for a short period of time determined by the setting of the time delay period of relay I13; the relay I13 closes so that its contactor I swings from an inoperative position into engage-.

ment with a stationary contact I96 of the relay. Closure of the time delay relay I13 in this manner effects energization of the coil I55 of relay I22 governing energization of the retracting solenoid' I I 4 of the valve unit I I9.

The coil I55 of the relay I22 is energized upon closure of the time delay relay I13 by a circuit leading from line LI .and including conductors I 56, I51 and the bridged contacts I59 of limit switch I39, conductor I10 and a branch I 91 thereof leading to the stationary contact I95 of the relay and across the contactor I95 engaging said stationary contact, a conductor I98 leadin from the contactor I95 to one side of the coil I55 of relay I22, and a conductor I99 connecting th other side of the coil with line L2.

The relay I22 has two sets of normally open stationary contacts 290 and 29I both of which are bridged upon energization of the coil I55. Bridging of the stationary contacts 209 establishes a holding circuit for the coil of relay I22 leading from line LI and including conductor I56, the now bridged stationary contacts I52 of the limit switch I49, a conductor 293 leading from the limit switch I49 to the now bridged stationary contacts 299 of relay I22, with the circuit continuin across the contacts 200' to the conductor I98 leading to one side of the coil I55, and from the other side of the coil to line L2 th-roughthe conductor I99.

Bridging of the stationary contacts 2M of the relay I22 connects the retracting solenoid II4 of the valve unit across the lines LI and L2 through conductor I56, the now bridged contacts I52 of Upon initial retracting motion of the feed slide" the cam I43 is carried awayfrom the button of limit switch I39 to cause'the contactor I5I of the switch to leave the stationary contacts I50 and re-engage the stationary contacts I49 of the switch in response to the biasing force on the contactor.

Dlll'il'lg the start of the return stroke of the feed slide, therefore, the contacts I50 of the limit switch I39 are opened and such opening of these contacts disrupts the energizing circuits to the electromagnetic valves V4 and V5 causing the same to close. Closure of the valve V4 shuts off the pressure to the recess 15 in the front of the feed head, while closure of the valve V5 shuts off the vacuum' to the recess 14 at the frontof;

the head.

fiisconnection of these chambers at the frontof the head from their sources of vacuum and pressure is necessary to prevent disturbing the metal powder injected into the die cavity at the time: the front portion of the head travels over the die cavity in the retraction stroke of the feed slide.-

In order to eifect cleaning off of the surface of the. die block in front of the die cavity, however, thecam M3 is designed to. hold the button of switch r39 depressed for a short time at the start of. the retracting stroke of the feed head but clears. the button of the switch just before the annular vacuum port 8'9 reaches the edge of the die: cavity [.3 adjacent thereto. Hence, the metal powder lying on the die block between the die cavity and the front of. the head is stirred up by the discharge of air or gas. under pressure from the. nozzles 86 and drawn into the vacuum recase: M through the annular vacuum port-89during rearward travel of the front portion of the head; toward the die cavity.

The: metal powder lying on they top of the die. blochrearwardly of the die cavity as well as. any excess over the die cavity itself is carried rearwardly over the block to. the apron behind the block by the wiping action. of the; resilient sealing; gasket 68,. to be stirred up by nozzles 86 and drawn off by the. vacuum, through port 89. at the back of the feed head; during the next feed stroke of. the head, it being recalled; that the pressure and; vacuum for the. rear recesses in the head. remain on. at all times.

Separation of the contacts I50: of the, limit switch I39 upon initial retracting motion of the feed: slide also disrupts the energizing circuits: for the time delay relays H2 and I13 which immediately de-energize to effect return of their contactors. I'M and I95, respectively, to their normal positions shown in the diagram.

Separation of the contactor I'M from the stationary contact I82 of the time delay relay I12 at this time eiiects de-energization of. the solenoid of the vacuum valve V3 thereby disconnecting the recess 55 in the center of, the upper head casting 52 from its source of vacuum, and reengages thecontactor I'M with its stationarycontact IBI; sothat the relay is reset and capable ofv completing the energizing circuits to the valves VI and V2 controllin the injection of metal. powder into the interior of the feed head and the pressure through the top center of the head uponv subsequent closure or bridging of the stationary contacts liiil the next time the-feed head is advanced to its operative position.

It is to be understood, of course, that energization of the solenoids VI and V2 depend upon bridging of the contacts I58 as well as engagement of the contactor H4 with its stationary contact. I8! of relayv I12.

' The solenoid [I43 controlling retraction of the feedhead effects complete retraction. of the feed head, and; the retracting stroke of the slide 3:I is terminated upon depression of the button of limit switch Mt by the cam I M; onthe feed slide to separate the contactor It'd of: the switch from its stationary contacts I52 and. to bring the contactor into bridging relationship with the stationary contacts I53 of the switch.

Since. the holding circuit for relay I22 controlling energization of the retracting solenoid H4 depends upon bridging of contacts I52. of. limit switch I40, the relay I22. is immediately. deenergized. by return of the feed. head to its. retracted.

position causin deenergization of solenoid: M4.

1 6 and return or the spool-like piston H 5 of the valve unit' toits neutral position.

As stated previously, the piston N5 of the valveunit when in its neutral position entirely disconnects the hydraulic drive cylinder 45- from the source of fluid pressure and consequently thefeed slide comes torest with the button of limit switch I40 held depressed and the contacts I53 of the switch bridged by the contactor I56 One of the features of the electrical controlsystem of this invention resides in the fact that it is possible toeffect initiation of the work cycle of the metal powder press at the time the feed head is brought to itsfully retracted position, and this may be accomplished by bridging of the contacts I 53 ofthe limit switch MB.

It will lee-noted that-the compressor cylinder I4" of the press is shown provided with an electromagnetic valve u-nit 2W similar to the valve unit I It controlling the drive cylinder 45. The valveunit 2 Iiiisprovided with pressing and retracting solenoids 2H and.- 2 I2, respectively, by which the opposite ends of the cylinder are connected with a source of fluid under pressure through the valve tosuccessively produce the pressure and retract-- ing strokes of the plunger It of the cylinder. This control mechanism is usually standard equipment on many metal powder presses and.- hence forms nopart of thepresent invention.

As indicated in the diagram, however, energizationof the solenoid 211- is adapted to con nect the upper end of the cylinder I4 with asou-rce of fluid under pressure and consequentlyprod-uce the downward compression stroke of the plunger t5 which enters the die cavity and compacts the powder therein against the upper end of the plunger le of the" ejector cylinder.

While-both solenoids 2i iand 2I2 for the valve unit 2H3 are customarily provided with controlrelays, only one such relay 21d has been illustrated. This relay forms part of the control system of this invention and is adapted to be ener gized to initiate the work cycle of the press.

The energizing circuit for the solenoid of the relay 2M leads from line LI through conductors I58 and I5? across the contactor the of the limit switch I40 which isin bridging engagement with the contacts I53 of the switch and ontoa" con-- ductor Z-Ifi leading toone side of the coil for relay 2M, with the circuit completed from the other side of the coil to line- L2 through a conductor 21.1.

The relay 2M has two sets of stationary con tacts 2+8 and 2 I-Sboth of which are bridged upon energization of the, coil of the relay in the de- One of the set of stationary contacts 2I9 leads to line LI. through a conductor scribed manner.

222' while the other connects with the conductor 2 I6 through a conductor 2'2I which also joins with onev of the. set of' stationary. contacts 2|.8 of the switch.

Bridging of the contacts 2I9 thusestablishes a holding circuit for the coil of relay- 214 leading from. line LI- through conductor 2'22 and the bridged contacts 219, ontothe conductor 22I which leads through the coil of the relay and to line L2 through-the conductor 2 I1.

Bridging or the contacts 218 of the relay 2M- establishes an energizing circuit for the pressel:

solenoid 2I1 I: of the valve unit 2W leading from line LI through the conductor 222 and seriallythrough both. sets of bridged contacts M9 and 21:8, onto a conductor 22$ connecting with one side. of thesolenoid: 2 H and through a conductor tionary contacts 2"! of relay H4 at the time of plunger 16 of the ejector cylinder IT, the electrical control instrumentalities with which the 224 connecting with the opposite side of the solenoid 2| I to line L2.

It is to be understood that the work cycle of the press is carried out automatically by controlin- 2I4 after completion of the compression stroke by the plunger 45 of the compressor cylinder, and

. effect energization of the retracting solenoidZlZ for "the valve unit 2th.

These control instrumentalities form no part of the present invention inasmuch as they may be considered standard equipment on the press.

It is sufficient to note that bridging ofthe stabridging of the stationary contacts its of the limit switch I40 eiTects energization of the coil 2H of the hydraulic valve unit 2m to initiate the pressing cycle.

After ejection of the metal compact by the press is provided elfect retraction of the plunger Of the ejector cylinder and return the same to its lowermost position forming the bottom of the die cavity, and this lowering motion of the plungfer It may be considered as the final motion of .the press.

As stated previously, the final motion of the press is utilized in the present control system to effect momentary closure of the automatic start switch I28 by the arm we carried by theplunger {l6 of the ejector cylinder i? so that the next efiects energization of relay iii through the closed contacts I49 of the limit switch 39.

Closure of the relay I2l effects energization of the feedsolenoid H3 of the four way hydraulic valve unit Ill) causing the feed cylinder to ad- Vance the feed head to a positioncentered over the die cavity I3 and determined by depression of the button of limit switch I39 by the cam I43.

This efiects de-energization of relay I2I and the-feed solenoid I I3 of the valve unit so that the feed head remains stationary over the die cavity, and makes contact in both time delay relays I12 and I73 thereby starting the aforementioned time delay periods.

Depression of the push button of limit switch I39 to bridge its contacts I50 also effects energization of vacuum control valve V and pressure control valve V4 both of which lead to the recesses at the front of the feed head.

concomitantly with bridging of the contacts I50 of the limit switch I39 the solenoids of valves 1 VI and V2 controlling the delivery of metal powder to the interior of the feed head and the air or gas pressure to the recess 55 in the center of the upper feed head casting 52, respectively, are energized to effect controlled injection of metal powder into the die cavity.

At the end of the time delay period of relay I72,

the valves VI and V2 are closed and the solenoid z! for valve V3 energized to subject the interior of the feed head to vacuum.

At the expiration of the time delay period for relay I13 the relay operates to effect closure of producing the retracting stroke of the feed head.

As the head starts to travel toward its retracted position limit switch I39 is reset breaking the en ergizin circuits for vacuum and pressure valves str'umentalities part of which, indicated at 225, 5

disrupt the holding circuit for the coil of relay ian r When the feed slide reaches the end of .its;.i'e= turn stroke, the cam I 44 thereon depresses the button of limit switch I40, effecting de-ener'g'i za= tion of solenoid H4 to, terminate the retracting stroke, and also efiects initiation of the work cycle of the press by causing relay 2| 4 controlling energization-of the presser solenoidxZII on valve unitZIfltoclose. n The manually operated valves I87 andv I88controlling vacuum and pressurev to the rear recesses in the feed head remain open all of the time to cooperate with the sealing gasket. in cleaning surplus powder off the surface of the die block. I

From the foregoing description taken in connection with the accompanying drawings;it will be readily apparent that the feed mechanismof this invention and the control system therefor operates in an entirely automaticmanner to leffect a more speedy and efficient charging of the die cavity of a metal powder press after each work cycle of the press.

What I claim as myinvention is: 1. A feed nozzle for filling a cavity with powdered material, comprising: a head having an outlet opening at its bottom leading from a chamber in the interior of the head; the head having an inlet passage leading to said chamber and through which powdered material entrained in gas may be delivered to said chamber for discharge through the outlet opening in the bottom of the head; a gasket carried by and projecting from the bottom of .the'head and encircling the outlet opening therein, said gasket providing a substantially air-tight seal between the bottom of the head and a surface upon which the head is positioned to form an enclosed space for connecting the mouth of the outlet opening with the mouth of a cavity opening to said surface; and the head havin an exhaust passage communicating with said space circumscribed by the gasket to vent the same during the charging of powdered material into the cavity.

2. A feed nozzle for injecting powdered material into a cavity which opens to a surface, comprising: a head having an outlet opening in its bottom leading from a chamber in the interior of the head; the head having an inlet passage leading to said chamber and through which powdered material entrained in gas may be delivered relay I22 and the energization of solenoid H4 7:

to said chamber for discharge through said out let opening in the bottom of the head; an apertured distributing disc disposed across said outlet opening; a gasket on the head projecting from the bottom thereof and encircling said distributing disc so that upon placement of the head on said surface with the distributing disc over the mouth of the cavity, the gasket together with the bottom of the head and said surface defines a substantially air-tight space connecting the outlet opening in the head with the mouth ofthe cavity; and means defining an exhaust passage in the head communicating with said space circumscribed by the gasket to provide a vent for the release of gas entering said space during the filling of the cavity.

3. The feed nozzle of claim 2 further characterized by the fact that said gasket is spaced from the periphery of the outlet opening in the bottom of the head; and further by the fact that the mouth of the exhaust passage -extends subst'antially completely arbund' -the outlt'operiing 'a'nd opens to the bottom of the head between" the periphery g of the outlet opening a-n'd the gasket. 4. A' feed nozzle forfillinga eavity withp'owdered material, comprising: a head h'avi'ng' a central chamber in its" interior;-' means *'defining -'a discharge passage leading fr'orn said chamber, rthe 'mouth of saidpassagebpening to the bottom ofthe'. head} means defini-ng an inlet passage lead- .ing tosaid chamber through whic-h powdered'ma- =.teria1 entrained in gas may be fed to the chamber for discharge from'the bottom-of the-head; a gasket secured to the underside of-the head-and completely surrounding-the mouth or the discharge passage in spaced relation toits' periphery, said gasket projeet'ing fror n -the bottom of the head so that upon positioning the head upon a --,sur face torwhich the mouth of the cavity opens, the bottom of the head is spaced above said surface and a sub'stantiaHy air tightspace is provid- &'ed-c0.nne'cting the mouth of the dischargepas asage with the mouth of 'the' -"ca'vity; 'and" '-means "defining winner and outerfchambe'rs in the head fiencircling .the mouth 0f the discharge passage with .the'iirmermost bf said charribrsicommuni- {gatingdirectly with said space circumscribed-"by the gasket but near the-pei iphery ofthe mouth of the discharge 'passage,"and thaoutermost of asaid chambers having communication with said 20 space through ports opening to the bottom of the head near thegasket and pointinginwardly toward the mouth of the discharge passage so that gas under pressure issuing from said ports tends to blow powdered. material accumulated on the supporting surface toward the mouth of the discharge passage and whereby suction in the innermost of said chambers draws oil? such powdered material blown inwardly as well as the gas issuing from the mouth of the discharge passageduring filling of the cavity with powdered material.

JOHN A. HARRINGTON.

REFERENCES CITED The following references are of record in-the file of this patent:

UNITED STATES PATENTS Number Name Date 204,307 Daff May 28, 1878 593,267 Adams Nov. 9, 1897 1,949,433 Russell Mar. 6, 1934 1,982,763 Russell Dec. 4,1934 2,054,476 Derry Sept. 15, 1936 2,127,994 Davis Aug. 23, 1938 2,133,027 Honig Oct. 11, 1938 2,206,000 Byerlein June 25, 1940 2,259,465 Hardy Oct. 21, 1941 2,435,858 Whitehead Feb. 10, 1948 2,448,277 Renier Aug. 31, 1948 

